EVAPORATION 373 Vertical Type.—Figure 12: The first vertical tube evaporator was built by Robert, and has the one great advantage over the horizontal type, that it can easily be cleaned with any ordinary flue cleaner. Figure 13: The same construction as the Robert evaporator with an addition of a very large downtake in the center to improve the circulation of the liquor. This type was first constructed by Claassen, and is now used to a large extent in the cane-sugar and malt-extract industries under the name of "Standard Evaporator." FIG. 18.—Original climbing-film evaporator (Kestner). FIG. 19.—Mantius rapid-circulation evaporator. Figure 14 shows an evaporator where the central downtake has been replaced by a large annular downtake. The steam chest does not form an integral part of the evaporator, but is placed inside the shell on separate supports. This construction was first built by Kauffmann, and introduced in the United States by Mantius. Figure 15: A vertical-tube evaporator with the steam inside and the liquor outside the tubes. The top of the tubes is closed, and the steam either enters through the main tubes (Sanborn), or through a small concentric tube (Pecqueur and Mantius). Film Type.—Figure 16 shows the construction of Yaryan, in which the liquor is passed successively through a number of coils at very high speed. Figure 17: A special type of evaporator, Lillie patent, with horizontal tubes, where a thin film of liquor is formed on the outside of the tubes by the use of pumps. Figure 18 shows the first type of a climbing-film evaporator (Kestner). The liquor passes through the tubes only once, and is discharged from the vapor dome directly to the next evaporator or storage tank.